Method and apparatus for tubal occlusion

ABSTRACT

A device for sterilizing females by occluding the uterotubal junction. The device includes a catheter with a releasable heat generating plug which is used to thermally damage the uterotubal junction and cause it to constrict around the plug, after which the plug is released from the catheter and left in place in the uterotubal junction.

This application is a provisional of Ser. No. 60/048,632, filed Jun. 5,1997 now pending Ser. No. 60/054,388 Jul. 31, 1997 now pending of whichthe following is a specification:

FIELD OF THE INVENTION

The present invention relates to an apparatus and method for permanentlyclosing body vessels such as veins, arteries, body tubes, etc. Thepresent invention particularly, though not exclusively, relates to theocclusion of the female mammalian fallopian tubes. In particular, thisinvention is directed to a relatively simple surgical procedure forsterilizing human females which may be performed in the physician'soffice.

BACKGROUND OF THE INVENTION

It is often desired or necessary for medical reasons to permanentlyclose body vessels such as veins, arteries, body tubes, etc. Ofparticular utility is an ability to close the fallopian tubes of womenfor sterilization purposes.

One method for sterilization in females is surgical tubal ligation, aprocedure in which the uterine tubules are tied and cut or clampedthrough an incision made through the wall of the abdomen. When doneendoscopically, the pelvic cavity must be pneumatically inflated usingan inert gas. Aside from injury due to over inflation, numerous cases ofthe formation of embolisms have been reported. Tubal ligation done witha laparotomy requires a surgical incision in the abdomen between 6 and12 centimeters long done under general anesthesia. Aside from permanentscar formation at the site of incision, there are reported cases ofdeath due to anesthesia complications.

Other methods for female sterilization have been investigated. In onetechnique, investigators have transcervically instilled the sclerosingagent quinacrine into the uterus and fallopian tubes to create apermanent closure of the fallopian tubes. Major drawbacks from thisprocedure are the need of repeat applications and a significant level ofside effects.

Another technique involves transcervically injecting a curableelastomeric composition such as silicone into the fallopian tubes in anamount sufficient to fill the portion of the oviduct adjacent theuterus. The elastomeric composition is allowed to solidify to therebynonsurgically block the tube. Erb, Method and Apparatus for No-Surgical,Reversible Sterilization of Females, U.S. Pat. No. 3,805,767 (Apr. 23,1974). This technique is time consuming, however, and requires a highlevel of technical skill both for the preparation of the silicone andfor performing the procedure.

Cohen, et al, Method for Tubal Electroligation, U.S. Pat. No. 5,556,396(Sep. 17, 1996) discloses a method for tubal ligation by providing anelectrically energizable electrode to a fallopian tube. The electrode isadvanced into the fallopian tube and energized to thermally damage thefallopian tube, thereby causing enough scarring of the fallopian tube topermanently occlude it. The Cohen patent is hereby incorporated byreference.

Others have proposed placement of an occlusive wire or coil within thefallopian tubes to occlude them. Ton, Endoluminal Coil Delivery Systemhaving a mechanical release mechanism, U.S. Pat. No. 5,601,600 (Feb. 11,1997), proposes placement of a Guglielmi detachable coil (typically usedfor vascular occlusion) deep within the fallopian tube, past theisthmus. The coil must be delivered into the fallopian tubes with adelivery catheter extending from the uterus into the fallopian tubes.

Many of the prior art sterilization methods require placement of anoccluding object or device deep within the fallopian tube.Theoretically, the prior art devices make sense. However, the fallopiantubes have proven to be very difficult to cross with any useful device.In the typical human anatomy, catheters and guidewires cannot alwaysnavigate through the fallopian tubes as required by the methods of theprior art.

Summary

The method of the present invention provides a technique ofsterilization, discussed in greater detail below, which involves thecollapsing of the uterotubal junction and/or fallopian tube around aplug to create total occlusion of the tube. Total occlusion of the tubeprevents male sperm from fertilizing female eggs, thus preventingconception.

The method comprises, in accordance with the present invention, thesteps of: (a) providing an elongated instrument assembly having a distalend portion, (b) inserting the distal end portion of the instrumentassembly through the vagina, across the cervix, and into the patient'suterotubal junction (uterotubal junction), (c) operating the instrumentassembly to deliver and control radio frequency (RF) energy from theinstrument, causing the tissue of the uterotubal junction to collapse onthe distal end portion, (d) detaching the distal portion of theinstrument to create a total seal of the uterotubal junction, (e)removing the remaining portion of the instrument from the patient.

The method can be modified to permit the sterilization of both fallopiantubes without removal and replacement of the catheter from the uterus tosterilize the second tube.

The fact that the tissue destruction is performed outside the fallopiantubes, close to the uterine cavity in the thick portion of theuterotubal junction substantially reduces the risk of bowel injury.Advancement of any device beyond the isthmus of the fallopian tubes orwithin the fallopian tubes is not necessary, although in some casesinsertion into the proximal portion of the fallopian tubes will beaccomplished. No caustic substances come into contact with theperitoneum, obviating unpleasant side effects, and total occlusion ofthe lumen virtually eliminates the risk of ectopic pregnancy.Furthermore, no special technique is required to perform the procedure.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partial view of the female reproductive system.

FIG. 2 is a drawing of the device used to deliver RF power and anoccluding plug to the uterotubal junction.

FIGS. 2a and 2b are close up views of the distal segment of the deviceincluding bipolar electrodes.

FIG. 3 is a drawing of the device with the distal section placed withinthe uterotubal junction before delivery of RF energy and detachment ofthe electrode (plug).

FIGS. 3a and 3b are close-up views of the uterotubal junction before andafter delivery of RF energy, illustrating detachment of the distalportion and removal of the remaining portions of the device.

FIGS. 4-7 describe various electrode designs for use with the device.

FIG. 8 is a side view of a coil shaped distal electrode.

FIG. 9 is a cross section of the delivery catheter.

FIG. 10 is a cross section of the electrode plug assembly disconnectedfrom the transcervical catheter.

FIG. 11 is a cross section of the occlusion device which uses laserenergy and a laser tip to occlude the fallopian tube.

FIG. 12 illustrates an embodiment of the catheter which uses ultrasoundenergy to occlude the fallopian tube.

FIG. 13 illustrates an embodiment of the catheter which uses cryogenicenergy to occlude the fallopian tube.

FIG. 14 is an overview of the female body illustrating major aspects ofthe sterilization method.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows some of the major elements of the female reproductivesystem. The uterus 2 is an organ of the female pelvis that has the shapeof a pear. It consists of a thick muscular coat, the myometrium 3, acavity having an inner mucosal lining of variable thickness called theendometrium 4, and a cavity referred to as the uterine cavity 5. Thecervix 6 defines the cervical canal 7 which is an inferior opening tothe vagina 8. The fallopian tube 9 is a hollow organ that connects theuterus to the ovary 10. The ovary is the organ that produces one or moreeggs during every cycle of a woman's reproductive life. In the humanfemale reproductive system, there is one uterus, two fallopian tubes andtwo ovaries (under normal conditions). The site where the fallopian tubeand uterus connect is called the uterotubal junction 11. It is a sectionof tubular shape of about 10 mm in length. Its inner diameter in theresting position is less than 1 mm, but when gas or liquid is pushedthrough the uterus and tubes, the diameter of the uterotubal junctionmay stretch up to about 2 mm. The uterotubal junction provides atransition between the uterus and the fallopian tube, and the area oftransition from the chamber of the uterus to the lumen of the uterotubaljunction is referred to as the ostium or cornu (marked with item number12). The area of transition between the ostium and the isthmus 13 of thefallopian tube is referred to as the interstitial portion (marked asitem 14). The ostium, uterotubal junction, interstitial portion, isthmusand fallopian tube are part of a pathway leading from the ovaries to theuterus, and this pathway is sometimes referred to as the uterine tube.

FIG. 2 shows the main components of the present invention. The first isan elongated tubular segment, better known as a catheter 20, thatcontains several significant components. The proximal section of thecatheter contains an electrical connector 21 to connect to an RFgenerator. Also located at the proximal section of the catheter is adeflection handle 22. When the handle is manipulated, the distal section23 of the catheter bends in a relative direction by means of amanipulation wire connected between the handle and distal cathetersection. By operating the actuator means on the handle, the distal tipbends 30 to 180 degrees from straight. (Where the transcervical catheteris used in conjunction with a steerable hysteroscope, the catheteritself need not be steerable.) The detachable electrode plug 24 ismounted on the catheter at the distal end of the catheter, and theproximal actuator 25 is mounted on the handle and connected to adetachment mechanism within the distal tip of the catheter.

The middle section of the catheter 26, (body), consists of a hollowtubular structure that contains the conductor(s), sensor wires,manipulation device and distal section anchor/release mechanism. Thissection protects the human body from these components and is required todeliver the distal tip portion to the proper location. The middlesection can be manufactured with stainless steel wire braid or windingto improve torque transfer. Improved torque transfer helps assist thedoctor with twisting the handle on the proximal end of the deviceallowing for the torque to transfer to the distal section of the deviceand aid in proper placement of the distal section to the uterotubaljunction. A coating can be applied to the shaft to increase itsradiopacity for X-ray procedures. The coating may include compounds suchas a barium sulfate loaded urethane or Pebax™ manufactured by Atochem.In addition, an echogenic coating can be applied to the shaft toincrease the catheter's visibility during ultrasound imaging. Thiscoating can include trapped air bubbles that provide an echogeniceffect. The catheter shaft may be made with a material loaded with airbubbles as well. Catheter shaft materials can be, but are not limited toPTFE sold under the tradename of Teflon® manufactured by DuPont, ETFE,polyethylene, polypropylene and polyvinylchloride.

FIG. 2a shows a simple bipolar embodiment for the detachable electrodeson the distal section 23 of the catheter. The electrode plug 24 containsthe proximal electrode 27, distal electrode 28, and the insulator 29 toelectrically and thermally insulate the electrodes, the anchor/releasemechanism 30 for the electrode and a temperature sensor. It alsocontains a soft catheter portion 34 to allow deflection when theproximal handle is manipulated. One conductor wire is attached to thedistal electrode and a second conductor wire is attached to the proximalelectrode. The length of the conductors is contained within the catheterbody to isolate it from the patient. The conductors are coated with anelectrically insulative material. The proximal end of each conductor isattached to the electrical connector 21. The electrical connector isthen connected to an RF generator.

FIG. 2b illustrates another embodiment for the bipolar electrode plug24. The electrode assembly includes two hot electrodes 35d and 35p, andtwo ground electrodes 36d and 36p mounted on the insertion portion 37 ofthe electrode plug 24. The insertion portion comprises the insulator 29and the electrodes. The attachment mechanism 30 attaches to the softcatheter portion 34, and is housed within the proximal section of theelectrode plug 24. The proximal section of the plug may be provided witha larger diameter cross section than the insertion portion, in order toform a shoulder or flange type surface 38 which will serve to limitinsertion of the plug and prevent insertion into the fallopian tubes.

The distal electrodes can be made from any electrically conductivematerial such as stainless steel, copper, Elgiloy™, MP35N, platinum,titanium, nitinol and various other materials and alloys. The surface ofthe distal electrode can be covered or finished with a porous design toencourage fibroblast and/or tissue ingrowth. Tissue ingrowth (possiblyreferred to as scar formation) around the electrode insures a permanentseal of the fallopian tube. Different shape configurations and undercutscan also be incorporated into the electrode design to insure a permanentseal of the fallopian tube. Various embodiments of bipolar and monopolarplugs may be adapted for use. For a monopolar device, there is only oneelectrode on the distal section of the catheter. A dispersive electrodeplaced on the patient's exterior creates the current path for themonopolar device. While this is unsuitable for devices attemptingthermal damage of the thin-walled fallopian tube, it should be suitablefor the thick portion of the uterotubal junction. The insulator 29 canbe made from any of the thermal and electrically insulative engineeringmaterials such as ceramic, polyetheretherketone, Ultem™ manufactured byGeneral Electric, phenolic, epoxy, Pebax™ and PTFE. The surface of theinsulator can be covered or finished with a porous design to encouragefibroblast ingrowth. The insulator can be manufactured from porousexpandable material such as Teflon. Use of expanded PTFE encouragestissue ingrowth and/or scar formation around the electrode insuring apermanent seal and preventing plug migration over time. The insulatormay be a coating applied over a conductive material.

The insulator can also be made from any of the bioresorbable orbioerodible materials such as polyglycolic acid (PGA), polylactic acid(PLA), polydioxanone (PDS), or any combination of them. The insulatormaterial can also be attached to the distal section of the plug toencourage tissue ingrowth and/or scar formation distally from the plugin the fallopian tube.

The proximal electrode 27 can be made from any electrically conductivematerial such as stainless steel, copper, Elgiloy™, MP35N, platinum,titanium, or nitinol or other alloys. The proximal electrode can belarger than the distal electrode. This creates a higher current densityin the tissue adjacent to the distal electrode and insulator, so thatcollapse of the fallopian tube is more pronounced in the insulator anddistal electrode portion.

The distal portion can also contain a temperature sensing device such asa thermocouple or thermistor. The sensor is connected for feedback to acontrol circuit that modulates RF power applied to the electrodesaccording to the signal received from the temperature sensor. Thecontrol circuit compares the signal from the temperature sensor to a setvalue and modulates the RF power applied to the electrode in accordancewith the set value. A predetermined temperature setting can also be usedto stop RF power delivery to the electrode. In this way over-heating ofthe uterotubal junction can be prevented and the possibility of bowelperforation minimized.

The procedure can be done under x-ray guidance, sonographically,hysteroscopically, or blindly. The procedure can be done under generaland local anesthesia or general anesthesia only or local anesthesiaonly, with the latter preferred. The device is inserted into the bodynon-invasively: through the vagina, through the cervix into the uterus.This device can be inserted into another device such as a hysteroscopealready positioned across the cervix.

By manipulating the proximal handle, the distal segment can be deflectedto assist in proper positioning of the distal electrode within theuterotubal junction or fallopian tube ostium or fallopian tube.

Impedance measurements are taken from the tip electrode(s) to assistwith proper positioning. For a bipolar device design, in the presence ofan electrolyte distention media (such as saline solution), impedancewill increase when the electrode is positioned properly within theuterotubal junction. It has been shown that this rise in currentresistance is due in part to the current path moving from theelectrically conductive media into the relatively higher resistanttissue within the uterotubal junction.

For a bipolar device in the presence of a non-electrolyte distentionmedia (such as sorbitol), impedance will decrease when the electrode ispositioned properly within the uterotubal junction. It has been shownthat this decrease in current resistance is due in part to the currentpath moving from the non-electrically conductive media into therelatively lower resistant tissue within the uterotubal junction.

For monopolar electrodes, in the presence of a non-electrolyticdistention media, the impedance will decrease when the electrode ispositioned properly within the uterotubal junction. It has been shownthat this decrease in current resistance is due in part to the currentpath moving from the non-electrically conductive media into therelatively lower resistant tissue within the uterotubal junction.Impedance monitoring can be accomplished through the electrode plug inthe RF embodiments, and it can be accomplished with the addition ofimpedance sensing electrodes in the laser and ultrasound embodiments.

It is also possible with the current device to deliver a localanesthesia to the uterotubal junction before the delivery of RF, laseror ultrasound energy. This will prevent any discomfort to the patientduring the procedure. It can be delivered in a liquid, gel, paste orpill form directly to the site. It can also be loaded into theelectrodes, laser hot tip, or ultrasound heating element, or into otherparts of the device such as the insulating portions of the RF electrodeassembly.

When the electrode plug is in position, controlled delivery of RFcurrent to the electrode(s) causes constriction of the vessel around thedistal electrode and insulator. Temperature and/or impedance monitoringcan be used to control or terminate RF current delivery to theelectrode. For temperature, the control circuit compares the signal fromthe temperature sensor to a set value and modulates the RF power appliedto the electrode in accordance with the set value. A predeterminedtemperature setting can also be used to stop RF power delivery to theelectrode. For impedance, the control circuit compares the signal fromthe electrode(s) to a set value and modulates the RF power applied tothe electrode(s) in accordance with the set value. A predeterminedimpedance setting can also be used to stop RF power delivery to theelectrode.

FIGS. 3 through 3b illustrate the procedure. FIG. 3 shows the uterus andthe structures of FIG. 1, including the uterus 2, cervix 6, vagina 8,fallopian tubes 9, uterotubal junction 11, the interstitial portion 14and the ostium 12. The catheter 20 has been inserted through the vaginaand across the cervix to the area of the ostium. The electrode plug 24has been advanced into the uterotubal junction 11, until the shoulder ofthe plug meets the junction and inhibits further insertion (the surgeonwill feel increased resistance to advancement, and will be able tovisually observe impact of the shoulder). Note that electrode plug 24 isinserted into a fairly thick area of the uterotubal junction 11 and theinterstitial portion, and has not entered the isthmus 13 or the thinwalled portion of the fallopian tube 9. Insertion only into theextra-fallopian length of the lumen will prevent the possibility ofburning or puncturing a hole in the fallopian tube and surroundingstructures. FIG. 3a shows the electrode plug 24 mounted on the catheterdistal tip 23 and inserted into the uterotubal junction 11 beforeheating of the plug and surrounding tissue with RF energy. Thesurrounding tissue of the uterotubal junction has been thermally injuredand has swollen around the plug and into the gaps between theelectrodes. When sufficient occlusion has been accomplished, the distalelectrode and insulator are detached from the body of the catheter. Thisis accomplished by operating the proximal actuator illustrated in FIG.2. FIG. 3b illustrates the plug after separation of the plug from theremainder of the device. The electrode plug 24, including the electrodes36d, 36p, 35d, and 35p, and the insulator 29, remain within theuterotubal junction. The surrounding tissue will heal in this condition,essentially surrounding and encapsulating the electrode plug to create amechanical lock on the plug. The electrode plug may be made in otherembodiments which permit detachment of the distal electrode section fromthe remainder of the plug. In this case, a distal electrode andinsulator remain in place while the remaining portion of the catheter,including the proximal electrodes, are removed from the body. In yetanother embodiment of the invention, there are several electrodesattached to the distal catheter to allow the physician to occlude bothfallopian tubes without withdrawal of the device. The electrode(s) andinsulator are designed to encourage fibroblast ingrowth to create ahermetic seal and prevent electrode migration.

FIGS. 4a through 4d illustrate various shapes for electrodes in thesimplest embodiment of the device. FIG. 4a is a cylindrical plug with aball point 39 at the distal end of the plug. FIG. 4b is a cylindricalplug with a bullet point 40 at the distal end of the plug. FIG. 4c is acylindrical plug with a flat cylinder top 41 at the distal end of theplug. FIG. 4d is a frustoconical plug with the small end 42 at theproximal end of the plug (it can be reversed). FIGS. 5a-5c illustrateembodiments of the electrode plug which provide for mechanicalinterlocking relationship between the shrunken uterotubal junction andthe electrode. FIG. 5a shows a pawn shaped electrode. FIG. 5b shows abarbell shaped electrode, with globular bells 43 on either end of theelectrode plug, separated by the insulator portion 29. FIG. 5cillustrated a barbell shaped electrode with an additional bell 44between the bells at either end. FIG. 5d illustrates a multi-flangedelectrode assembly, with several flanges 45 extending outwardly from theinsulator portion 29. FIGS. 6a through 6c illustrate various forms forthe proximal end of the electrode plug, making up the proximal shoulder38. FIG. 6a illustrates a simple flange 46 on the proximal end of theelectrode assembly 24, while FIG. 6b shows a mushroom shaped flange 47,and FIG. 6c illustrates a contoured flange 48. These shapes may beapplied to the proximal end (the uteral side of the plug) in order tolimit the insertion of the plug into the fallopian tube. FIG. 7 shows aplug having a screw thread 49 outer contour.

FIG. 8 illustrates a coil-shape configuration of the distal electrodeplug. By manufacturing the electrically conductive material into a wireor strip, it is possible to wind the material over the insulativematerial to form a coiled electrode. A bipolar coiled plug is madepossible by incorporating two separate wires parallel to each otheralong the coiled length. Thus FIG. 8 includes a helical ground electrode50 and a helical hot electrode 51 coiled in parallel about insulatedplug 52 to form the entire plug assembly 53. The winding pitch or anglebetween wire and the insulative material being wound on can vary throughthe plug. By varying the pitch angle, it is possible to create differentcurrent density fields for the plug. The pitch can vary from 0°(parallel to the plug's major axis) to 90° (perpendicular to the plug'smajor axis). In one embodiment, the pitch remains at 0° for the lengthof the plug and is not wound at all.

FIGS. 9 and 10 show cross sections of the delivery catheter withmechanism for delivering energy to the heating tip and disconnecting thetip from the remainder of the catheter. Transcervical catheter 20 isshown housed within the working channel of a hysteroscope 54. The distaltip 23 of the transcervical catheter 20 houses the electrode assembly24. The electrode plug 24 is a bipolar electrode plug, with a centralbore 55 which receives the central conductor assembly 56. The centralconductor assembly comprises the necessary wiring to carry energy to theelectrode assembly. The electrode assembly includes a electrode plug 57with a mating assembly 58 at its proximal end 59. The proximal end ofthe plug is flared, with shoulders 38, designed to ensure that theelectrode is not inserted beyond the uterotubal junction. Groundelectrodes 36d and 36p and hot electrodes 35d and 35p provide bipolar RFenergy to any tissue outside the plug. The electrodes are connected tothe remainder of the catheter through electrical contacts 60, and thesecontacts are further connected to ground wires and hot wires coiled ontothe central conductor assembly 56. The mating assembly 58 includes areceiving bore 63 for receiving the central conductor assembly. Thedistal end of the transcervical catheter likewise has a receiving bore64 for receiving the spring loaded tangs or detentes 65 which are biasedtoward the center of the device, but held in radially expanded conditionby the thickness of the central conductor assembly 56. The tangs 65extend into matching receiving holes 66 in the distal end of theinsertion catheter 20. The electrical ground wires and hot wires areconnected to the RF generator which is outside the body, connected tothe proximal end of the transcervical catheter.

In use, as discussed above, the hysteroscope and transcervical catheterare inserted into the uterus through the cervix. Using the hysteroscope,the physician can locate the ostium of the fallopian tube, whichcorresponds to the uterotubal junction. The physician advances thetranscervical catheter out of the hysteroscope, and inserts the pluginto the uterotubal junction until the shoulders of the plug are firmlyseated in the uterotubal junction. Electrical energy is applied throughone or more of the electrodes, grounded through the ground electrodes.When the uterotubal junction has been thermally damaged, it collapsesand constricts about the electrode plug. The outer surface of theelectrode plug is irregular, allowing mechanical interlock between theuterotubal junction and the plug when the plug constricts over the plug.After heating, the central conductor assembly 56 is pulled proximallywhile the catheter 20 is held in place. When the central conductorassembly 56 is pulled distally to the point where it clears the tangs,the tangs resiliently rebound to the center of the catheter and fall outof the receiving holes 66, as illustrated in FIG. 10. Should anyresistance be encountered, the shoulder 67 on the transition of thecentral conductor assembly 56 may be used to push gently on theelectrode plug while gentle force is applied to the catheter. Thedeployed plug is left in place to provide permanent occlusion of thefallopian tube. (The process is repeated for each fallopian tube.)

The RF energy may be supplied by any one of numerous RF energygenerators available commercially. Although RF energy is currentlypreferred, microwave energy may also be used, and microwave energygenerators suitable for use include such devices as the Prostatronmicrowave generator currently used for application of microwave energyto the prostate. Microwave power in the frequency of about 100 MHz to14,000 MHz will also provide sufficient thermal damage to the fallopiantube to initiate collapse and constriction around the electrode.

FIG. 11 illustrates an embodiment of the catheter which uses laserlight, rather than RF energy, to provide the heat necessary to thermallydamage the fallopian tubes and cause them to constrict. In addition tothe parts already discussed in relation to the RF embodiment, the laserdevice shown in FIG. 11 includes a laser light source (not shown), acentral conductor 56 comprising fiber optic fiber 70 capable ofdelivering laser light from the laser source to the tip of theelectrode, and a laser heating tip 71 disposed at the distal end of thecatheter. The fiber optic fiber is releasably attached to the heatingtip with a mechanism such as the releasable detentes described above.(Other mechanisms may include press fitting the fiber optic into areceiving bore in the heating tip so that it may be pulled out of thetip after heating, maintaining the tip in place with force from thecatheter outer tube. The optical fiber may also be glued or melted intothe tip, and simply snipped with endoscopic cutters after heating.) Forthis application, laser light sources are commercially available for avariety of other purposes, and these may be readily adapted for use insupplying heating light for the fallopian tubes. The heating tip 71 is aplug of silicone, bioglass or other transparent tip suitable for laserheating, and in this case it is cylindrical. The fiber optic is aimed atthe proximal end of a necked down detente holding pin 73, which isinserted into the receiving bore of the heating tip. The distal end ofthe fiber optic fiber and the distal end of the receiving bore arehighly polished to permit maximum transmittance of laser light into thetip. A reflective surface 74 is applied to the distal face of the tip toreflect laser light that reaches the distal face back into the plug. Theplug is loaded with dispersive particles (silica, alumina or titania)which serve to disperse the laser energy throughout the plug and convertthe energy into heat. When the plug is heated in this manner, it heatsthe surrounding uterotubal junction tissue to affect the thermal damagewhich is desirable in the sterilization method. Laser light sources andpower ranges typically used for such applications of laser thermaltreatment are expected to be safe and sufficient for use in applicationto the uterotubal junction.

FIG. 12 illustrates an embodiment of the catheter which uses ultrasoundenergy, rather than RF energy, to provide the heat necessary tothermally damage the fallopian tubes and cause them to constrict. FIG.12 shows the tip of the device, including the plug 75, the transcervicalcatheter 76, the piezo-electric crystal 77 and electrical conductors 78.The plug is connected to the catheter outer tube 72 of the catheter witha release mechanism similar to that shown in the earlier figures. Thecoupling element 79 sonically couples the transducer to the plug, andalso mechanically couples the transducer to the plug. The couplingelement also includes a small diameter distal extension which fits intothe bore of the plug during delivery and heating, and permits release ofthe tangs 65 when the central conductor is pulled proximally and thewide proximal portion 80 clears the tangs. Excitation of thepiezoelectric crystal with electrical impulses delivered through thewires will cause the plug 75 and surrounding tissue to heat up, therebycausing the thermal damage to the uterotubal junction desired to causecollapse around the plug. Again, when the uterotubal junction collapsesaround the plug, the plug can be disconnected from the rest of thetranscervical catheter and left in place. Ultrasound energy in the rangeof 10 KHz to 4 MHz may be applied to effect thermal damage.

FIG. 13 illustrates an embodiment of the catheter which uses cryogeniccooling, rather than heating, to provide the thermal damage necessary tocause the fallopian tubes to constrict. FIG. 13 shows the tip of thedevice, including the detachable cryogenic plug 84 mounted on the tip ofthe transcervical catheter 20. The detachable plug in this instancecomprises the tip of a cryosurgical probe of the type that uses liquidnitrogen. Cooling of the plug is accomplished by cryogenic cooling ofthe jacket 85 which fits closely within the plug. The cryogen supplyline 86 communicates with the annular lumen 87 formed between the jacket85 and the supply line. The supply line includes a port 88 at the distaltip, to distribute cryogenic fluid into the jacket. Liquid nitrogen orother cryogen is supplied to the probe through the supply line, andexhausts out the annular lumen and the gas return line 89. Afterapplication of cryogenic cooling, the gas line is pulled proximallyuntil the jacket clears the tangs 65 of the release mechanism, at whichpoint the tangs release the catheter 20 and the plug is left in place.

Another embodiment of the device is one which accomplishes conductiveand convective heating through the plug to accomplish the same results.There are several other ways to heat the fallopian tube through the plugby conductive and convective techniques. For example, AC or DC currentcan be delivered directly through the plug to create resistive heatingof the plug which in turn generates a hot surface on the plug. Anotherpossible technique is the delivery of a hot gas or hot liquid throughchannels of the catheter to the plug.

A plug could be designed with a resistive element placed with the plugto heat the plug and its surface. Heat would be transferred to theuterotubal junction by conduction and/or convection. Conduction of heatfrom the plug surface to the uterotubal junction is accomplished byplacing the plug in direct contact with the uterotubal junction.Convection of heat from the plug surface to the uterotubal junction isaccomplished by transfer of heat from the plug surface to fluids in thearea of the plug such as body fluids or artificial liquids, and thisfluid in turn transfers heat to the uterotubal junction

FIG. 14 illustrates the overall method of using the devices described inthis patent. The patient 1 lays on an operating table 90, in positionsimilar to that used for a gynecology exam, providing access to thevagina 8. Access to the cervix 6 and uterus 2 is facilitated byinsertion and opening of the speculum 91, which is locked to theoperating table 90 with clamping mechanism 92. The physician inserts thehysteroscope 54 to find and inspect the opening into the fallopian tubes(called the ostium), and then inserts the transcervical catheter 20 andadvances the transcervical catheter until the plug is seated in theostium of the fallopian tube. When the plug is properly positioned, thephysician will then use the catheter locking mechanism 93 (theillustrated locking mechanism is a set screw installed on thehysteroscope access port 94) to fix the transcervical catheter in placeand prevent accidental removal of the plug during the procedure orduring release of the plug. The speculum clamp and catheter lockingmechanism form a locking jig which includes one clamp for fixing thescope to the operating table and a second clamp for securely holding theproximal end of the transcervical catheter. (With the transcervicalcatheter locked in place in this manner, the physician may safely applyenergy to the releasable tip without fear of inadvertently pulling theplug uterotubal junction and misapplying the required energy.) Thephysician then applies energy sufficient to cause the uterotubaljunction to collapse about the catheter tip. After collapse andconstriction has been confirmed (this may be done visually through thehysteroscope, or by comparison of electrode impedance in the RFembodiments), the physician will hold the outer body of thetranscervical catheter firmly and pull the central conductor from theplug. (Again, with the transcervical catheter locked in place, thephysician may safely withdraw the central conductor from the plugwithout fear of inadvertently pulling the plug from the thermallydamaged uterotubal junction.) With the central conductor removed fromthe plug, the catheter should fall away from the plug. The physicianwill then remove the catheter. For complete sterilization, the physicianwill then repeat the procedure on the other side of the uterus. (Variousembodiments of locking mechanisms may be used, and will suffice toimmobilize the catheter in relation to the patient by any locking means.Where a hysteroscope is not used, or is provided without the lockingscrew as illustrated, it will suffice to lock the catheter to thespeculum. It will also be sufficient to lock the speculum to thehysteroscope and use the friction between the working channel of thescope and the catheter to stabilize the catheter and avoid excessivemovement of the purse. The number of possible locking mechanismembodiments is vast.)

Immediately after delivery of the RF energy to the targeted tissue,several stages of tissue response will occur in the healthy female.First, the damaged tissue will undergo an acute inflammatory response.In this stage, serum and white blood cells exit from the blood vesselsnear the tissue and move into the interstitial space between the cells.This process is called edema. This process is accompanied by the releaseof products from the mast cells, which increase the vascularpermeability to serum and white blood cells, increasing the edema. Giantcells called macrophages then move into the damaged tissue and startdigesting the thermally damaged cells.

The next stage of response is the healing stage, in which repairmechanisms take place to restore the uterotubal junction to its originalcondition. In this stage, cytokines and other products released by themast cells stimulate the fibroblasts of the conjunctive tissue (underthe endosalpinx) which duplicate and migrate into the area of thedestroyed tissue. The fibroblasts then produce a matrix of gel likematerial and fibers in which the fibroblasts proliferate. This processis called colonization, and continues until the entire damaged area isfilled with fibroblasts. The blood vessels in the injured area form budswhich grow into the new fibroblast matrix and revascularize the newlyformed tissue.

The plug which is left behind in the uterotubal junction will bemaintained in place by the constrictive action of the damaged tissue,during the healing process. As an aid to long term retention, the plugis porous to a degree which allows endothelial tissue and/or conjunctivetissue of the uterotubal junction to grow into the pores of the plug.The presence of the artificial matrix such as the plug provides anopportunity for the fibroblasts to grow into the plug and favorsocclusion of the fallopian tube in the area of the plug. To enhancetissue adhesion to the plug, each of the plugs illustrated above may bemade of a porous material (metal, glass, ceramic or other material) withpores ranging from about 1-400 microns. The pores may be natural to thematerial, or they may be manufactured into the material. (For example,metal plugs with pores may be manufactured as reticulated or foamedmetals according to known techniques.)

Tissue in-growth can be promoted by application of in-growth promotingcompounds such P15 or HEP III to the porous plug. Such agents thatpromote either the attachment of cells to the plug or the cellulargrowth deep into the pores and surface features (nooks and crannies) ofthe plug. Examples of such agents include protein coatings such ascollagen, fibronectin, and transforming growth factor beta, or asynthetic polypeptide coatings such as P15(Gly-Thr-Pro-Gly-Pro-Gln-Gly-Ile-Ala-Gly-Gln-Arg-Gly-Val-Val) or HEP III(GLy-Glu-Phe-Tyr-Phe-Asp-Leu-Arg-Leu-Lys-Gly-Asp-Lys), The manufactureof these compounds is well described in Bhatnagar, Synthetic CompoundsAnd Compositions With Enhanced Cell Binding, U.S. Pat. No. 5,635,482(Jun. 3, 1997) and Tsilibary, Prosthetic Devices Coated With APolypeptide With A Type IV Collagen Activity, U.S. Pat. No. 5,152,784(Oct. 6, 1992). Coating of the device by these proteins or polypeptidescan be accomplished by dipping the plug into a solution or liquidsuspension of the coating. This may be done immediately beforeimplanting the plugs into the uterotubal junction, merely by dipping orglomming P15 suspension onto the plug. The coating may also be appliedduring manufacture using dipping and coating techniques commerciallyavailable from such companies as Peptide Innovations, Inc. ofSouthfield, Mich. Additionally, the in-growth promoting compound may beinjected to the vicinity of the plug after the plug has been implantedor before implantation. Although heat will be generated in the vicinityof the plug, the in-growth promoting compound is not damaged.

The P15 compound appears to permit direct attachment of new endothelialcells to the plug material, and the endothelial cells are furtherattached to the uterotubal junction, thus securing the plug in place.The compound also appears to encourage endothelial growth sufficient tocreate a matrix of endothelial cells which is mechanically intermingledwith the porous structure of the plug.

The power requirements and length of time that energy must be applied tothe uterotubal junction are modest, on the order of a few watts of powerfor several seconds. In initial experiments, a range of power andapplication time proved useful in constricting body tissue. In oneexperiment, we tested the effects of RF energy on bovine coronaryarteries. A catheter was placed within the arterial structure and 10watts of RF energy were delivered to the distal electrode for about 10seconds. The artery constricted tightly on the catheter tip electrode.The diameter of the artery was measured at 0.064 inches with about 3 cmof the artery cut out of the myocardium. The experiment was repeated andthe catheter was slowly dragged through the artery while the RF energywas delivered. The artery and its surrounding tissue were cut in halffor observation. The RF energy delivered through the electrodeconstricted and closed the artery.

In a second experiment, we tested the effect of RF energy appliedthrough a catheter on a uterus and fallopian tubes of a large sow (500lbs.). We separated the uterotubal junction, fallopian tubes and ovariesfrom the reproductive system. We then placed a 7F steerableelectrophysiology catheter with a 4 mm long tip through the uteral endinto the fallopian tube. We applied 5 watts of power for 15 seconds.This caused necrosis, tissue discoloration and occlusion at theelectrode position. A small amount of force was required to remove theelectrode.

In a third test, we tested the seal provided by a removable electrodeafter RF treatment. We inserted a dumbbell-shaped electrode into theuterotubal junction of a large sow, and applied ten watts of energy for20 seconds. This caused necrosis, tissue discoloration and occlusion atthe electrode position. A tensile tester was then attached to theelectrode wire and pulled up to a force of 0.5 pounds without dislodgingthe electrode. With the electrode left in place, we placed a syringeneedle into the distal section of the fallopian tubes and tied off thefallopian tubes around the needle with suture. We then attached an ACSPTCA indeflator containing diluted blue dye to the needle and appliedpressure at about 20 psi for 15 minutes. We then attached a syringe ofpure dye to the needle and applied a relatively high amount of pressurefor 2 minutes. Blue dye was observed dripping out of the distal sectionof the fallopian tubes, through the tied off segment around the needle.None of the dye leaked past the plug into the uterus.

Variations in the devices presented above are expected to arise inpractice of the inventions. For example, the optimal power settings andtime for application of energy will most likely be refined with broaderexperience with the devices. It is expected that additional material forthe plug will be developed and employed in the practice of theinventions. It is also expected that new in-growth promoting compoundswill be discovered and applied in the practice of inventions. The plugmay also be designed to be removed at a later date, either by removing acentral core or by collapsing in on its self.

Finally, although the inventive methods and devices have been describedin the environment of human sterilization, they may be applied innumerous animals for which sterilization is often desired. Thus, whilethe preferred embodiments of the devices and methods have been describedin reference to the environment in which they were developed, they aremerely illustrative of the principles of the inventions. Otherembodiments and configurations may be devised without departing from thespirit of the inventions and the scope of the appended claims.

We claim:
 1. A method of sterilizing a female, said method comprisingthe steps of:(a) providing an elongated instrument assembly having adistal end portion; (b) inserting the distal end portion of theinstrument assembly into the patient's uterotubal junction; (c)operating the instrument assembly to deliver radio frequency energy fromthe instrument to the uterotubal junction, causing the tissue of theuterotubal junction to collapse on the distal end portion; (d) detachingthe distal portion of the instrument from the remainder of theinstrument; (e) removing the remaining portion of the instrument fromthe patient.
 2. A method of sterilizing a female, said methodcomprising:providing a catheter having a plug releasably mounted on thedistal end of the catheter; and providing an energy source operablyconnected to the plug and capable of heating the plug; inserting thecatheter into the uterus of the female, and inserting the plug into auterotubal junction of the female; operating the energy source to heatthe plug, thereby causing the tissue of the uterotubal junction tocollapse upon the plug; releasing the plug from the distal end of thecatheter.